There is a need for a volumetric feeder capable of feeding up to 300 tons per hour of granular material in the form of coal, rock, limestone, etc. from a hopper to consumption apparatus such a coal-fed power plant. The feeder must be capable of operating in an environment which is at an elevated temperature and dirty for long periods of time with minimum maintenance and with all components being readily accessible for maintenance. Commercially available feeders are not readily adaptable for such purpose and/or do not meet the specifications required.